In recent years, a substrate processing apparatus for polishing a surface of a substrate such as a semiconductor wafer has been used. The substrate processing apparatus is composed of a polishing unit for polishing a substrate, a cleaning unit for cleaning and drying a substrate, a loading and unloading unit for conveying a substrate, and the like, for example. The substrate processing apparatus feeds a substrate fed into the loading and unloading unit into the polishing unit to polish the substrate, for example. In addition, the substrate processing apparatus feeds the substrate after polishing to the cleaning unit to clean and dry the substrate. Further, the substrate processing apparatus ejects the substrate after finishing the drying from the loading and unloading unit to the outside of the substrate processing apparatus.
The substrate processing apparatus is divided into the plurality of units described above when delivered to an operation place such as a semiconductor plant. The substrate processing apparatus is installed by assembling the respective units after the units are delivered. The substrate processing apparatus is leveled when installed.
That is, the substrate processing apparatus is required to keep each of the units horizontally as well as to have an even height level for each of the units in order to apply various kinds of processing to a substrate. Thus, each of the plurality of units includes a lifting device (leveling device) between the units and a floor (installation surface of the units) to support self-weight of each of the units as well as to adjust height from the floor.
Usually, a plurality of lifting devices is provided in each of the units. The substrate processing apparatus is capable of leveling the unit by adjusting height of each of the lifting devices of the unit. In addition, the substrate processing apparatus is capable of adjusting a height level among respective units by adjusting height of each of the lifting devices of each of the units.
An adjuster foot provided with a screw structure in a vertical direction is generally used as the lifting device. In addition, a substrate processing apparatus provided with a vibration isolator, for example, sometimes adjusts a height level of units by allowing the units to be loaded on wedge-shaped lifting devices that are arranged on an installation surface in advance.
When maintenance of a unit of a substrate processing apparatus is performed, for example, it is difficult to perform the maintenance while a plurality of units is assembled. Thus, a unit of a maintenance object is removed from the substrate processing apparatus to perform the maintenance.
In conventional arts, it is known that, in order to remove a unit of a maintenance object from a substrate apparatus, the unit is extracted and conveyed by using a caster leg provided with a roller capable of rolling in an extracting direction of a unit, whose length is adjustable.